US Central Command say more than 10,000 armed forces members, as well as warships and planes, are involved in the blockade.

⁠The US military ⁠said its blockade of Iranian ports has been “fully implemented” and economic trade entering and leaving Iran by sea has been “completely halted”.

In a post on social media, US Central Command (CENTCOM), which is responsible for military operations in the Middle East and is leading the war on Iran, said the blockade is being enforced against vessels of all nations “entering or leaving coastal areas or ports in Iran”.

“An estimated 90% of Iran’s economy is fuelled by international trade by sea. In less than 36 hours since the blockade was implemented, US forces have completely halted economic trade going into and out of Iran by sea,” CENTCOM Commander Admiral Brad Cooper said in a statement late on Tuesday.

CENTCOM said that more than 10,000 sailors, Marines and US Air Force personnel are taking part in the operation and that, in the first 24 hours, six merchant ships had complied with US orders to turn around and “re-enter an Iranian port”.

The Reuters news agency said that a US Navy destroyer interdicted two oil tankers attempting to leave Iran on Tuesday, a day after the blockade went into effect, and instructed them to turn around.

The ships had left Iran’s Chabahar port on the Gulf of Oman and were contacted by the US warship via radio communication, an official told Reuters on condition of anonymity.

US President Donald Trump is hoping the blockade will force officials in Tehran to accept Washington’s terms for ending the US-Israel war on Iran. He announced the blockade after weekend talks broke down between US and Iranian negotiations in Pakistan, which had followed a ceasefire announcement that halted attacks.

CENTCOM said ⁠no ships have made it past the US blockade since it went into effect on Monday at ⁠10am in Washington, DC (14:00 GMT).

Abas Aslani, a senior research fellow at the Center for Middle Eastern Strategic Studies in Tehran, said on Wednesday that Iranians believe the US is now hinting at renewed peace talks to ease the shock of the blockade on the global oil market.

Oil prices had jumped above $100 per barrel before easing on hopes of further ⁠talks between the two sides.

Tehran considers the blockade a violation of the ceasefire, and this “can complicate the situation”, Aslani added.

“The ceasefire, which is currently in place, is a very fragile one,” he said.

“We are waiting to see what will be the reaction from Iran.”